Samsung LNS2641D 26-Inch LCD HDTV lost its picture

Hi,

We were watching TV last night, and the picture of our Samsung 26 in LCD HDTV went completely blank. There is a slight bit of light when you turn it on, but no picture at all, not from TV, or DVD player. The TV is about 2 years old and we've had no problems up until now. Any thoughts?

LA32R81BD working fine - then no picture, sound is fine, will not work thru DVD, or any source, no menu nothing on screen its all black. Get channel display when power on with buzzing sound but no channel display when changing channelLA32R81BD working fine - then no picture, sound is fine, will not work thru DVD, or any source, no menu nothing on screen its all black. Get channel display when power on with buzzing sound but no channel display when changing channel

I'm afraid that while their intention was good, that most the posted solutions miss the mark. Let me guide you thru the diagnosis and possible cure. This is detailed and lengthy, since these points appear often in LCD TV/Monitor repair.You may wish to warm up your soldering iron and skip to Step (11) for the repair procedure.

(1) We know that much of the Main Power Supply is working since many of the audio, video and digital processing sections appear to be working (sound, remote control, tuner, and video out).

(2) We know that the Backlight Inverter is working.Even thought the screen appears to be dark, light from the backlight tubes can clearly be observed.Further, even thought the screen is dark, you *can* observe a small amount of the backlight thru the screen.

(3) When working on LCD TVs and Monitors, the typical problem is backlight failure.(Fortunately this is NOT the case here.)Backlight failure is most often due to Backlight Inverter failure, or Main Power Supply failure.Rarely do the bulbs fail outright (although occasionally thru abuse a CCFL tube is cracked or shattered).

(4) The typical failure mechanism on LCD TV/Monitors that have many in-service hours on them is CCFL tube aging.As the CCFL tubes get older they require increasingly higher voltages to maintain the proper regulated current thru them which in turn creates the correct light output.The higher voltage is often beyond the design limit of the Backlight Inverter leading to component failure.Typically discharge breakdown arcing on the output transformers (that drive the CCFL lamps), or drive transistor failure in the Backlight Inverter power supply.Alternatively, the Main Power Supply may fail.Typically the Main Power Supply supplies +12V, or +15V, or a higher voltage (+24V?) to the Backlight Inverter subsystem.Once again, as the lamps age, more current is drawn, and if the Backlight Inverter doesn't fail outright, it draws excessive current from the Main Power Supply leading to either Main Power Supply failure.Alternatively, the Main Power Supply protects itself by shutting down once the excessive current is detected.This can often be seen as "monitor cycling" where by a LCD Monitor will initially power up, but subsequently cycles every few seconds as the Backlight Inverter draws too much current causing the Main Power Supply to shut down.Then, after a brief recovery period, the cycle repeats.

(5) Another failure mechanism, that should not be overlooked, is Electrolytic Capacitor failure.The Internet has many sites documenting either manufacturing defects in Electrolytic Capacitors used in any of the subsystems (Backlight Inverter, Main Power Supply, Digital Signal Processor, etc.).However, more often than not, Capacitor failure is due to component stress-due to the high ripple currents present in inadequately designed switching power supply subsystems.Additionally, many inferior Electrolytic Capacitors of Chinese origin are inadequately designed-they lack trace chemicals in the Electrolyte necessary to assure long service life.

(6)If you suspect any of the mechanisms described which cause an absence of CCFL backlight, you can often use a small pocket flashlight, and observe the screen image *is* in fact present on the LCD panel, but in the absence of sufficient backlight, you mistakenly believed the LCD panel to be dead.

(7) This is not the case here.We can clearly see that the CCFL backlight *is* lit, but we also do *not* observe any image on the LCD panel, even with an external flashlight.

(8) Thru this diagnosis of exclusion we assume that either the LCD panel itself is defective, or that the LCD panel is not receiving the correct drive signals from the Digital Signal Processor subsystem.

(11) It turns out that the main board that interfaces to the LCD panel drivers has a fuse which typically blows.I have no explanation for its failure, but suspect it is operating near its design limit, so with time may have stressed and blown.(As opposed to being blown thru some catastrophic downstream failure.)

(12) Initially, in my repair, I disassemble the entire board and protective metal cover.Once I located the fuse, I realized that an on-chassis repair could be done, and this is my recommendation to you.That way you avoid stressing the delicate flex-connectors that attach to the LCD panel.

(13) WARNING:DANGEROUS HIGH VOLTAGE PRESENT!Disconnect from the AC Mains before attempting to disassemble the unit!

(14) The first photo shows the LCD TV with the back shell removed.Disassembly is straight-forward, I'll leave it to you to figure out.

(15) In the photo, the Main Power Supply is shown in the center.The Backlight Inverter Power Supply is at the left.On the right, under the metal shield, is the Digital Signal Processor which contains the Audio / Video inputs and outputs as well as the Tuner.

(16) The cable bundle exiting from the Digital Signal Processor connects to the bottom of the LCD Panel Drive Board show at the top center of the photo.Right near the connector entrance is the defective (blown) fuse.

(17) The second photo shows a close-up of the defective fuse.The fuse is marked with the letter "P".The Reference Designator is CP101P.It is adjacent to C11.

(18) Before attempting a repair, use an ohm-meter to verify that the fuse is open.If the fuse is good, then your problem is elsewhere, and this procedure won't help you.

(19) The repair procedure is to bridge the fuse "P" with a small strand of wire.It is barely visible in the photo.The "P" fuse is left in place, and the wire soldered across it to the left.This is a delicate operation and requires a fine tipped soldering iron, good eyesight and magnifying glass, and a steady hand.Use a teenager if necessary.

(20) Use the ohm-meter to verify continuity of the bridged fuse.Check for shorts or excess solder.

(21) Reassemble the unit.(No need to leave those dangerous voltages exposed for testing.)

(22) If all went well, the TV is now repaired.(My repaired TV has been operating for six months now.)

(23) Enjoy!

(11) It turns out that the main board that interfaces to the LCD panel drivers has a fuse which typically blows.I have no explanation for its failure, but suspect it is operating near its design limit, so with time may have stressed and blown.(As opposed to being blown thru some catastrophic downstream failure.)

(12) Initially, in my repair, I disassemble the entire board and protective metal cover.Once I located the fuse, I realized that an on-chassis repair could be done, and this is my recommendation to you.That way you avoid stressing the delicate flex-connectors that attach to the LCD panel.

(13) WARNING:DANGEROUS HIGH VOLTAGE PRESENT!Disconnect from the AC Mains before attempting to disassemble the unit!

(14) The first photo shows the LCD TV with the back shell removed.Disassembly is straight-forward, I'll leave it to you to figure out.

(15) In the photo, the Main Power Supply is shown in the center.The Backlight Inverter Power Supply is at the left.On the right, under the metal shield, is the Digital Signal Processor which contains the Audio / Video inputs and outputs as well as the Tuner.

(16) The cable bundle exiting from the Digital Signal Processor connects to the bottom of the LCD Panel Drive Board show at the top center of the photo.Right near the connector entrance is the defective (blown) fuse.

(17) The second photo shows a close-up of the defective fuse.The fuse is marked with the letter "P".The Reference Designator is CP101P.It is adjacent to C11.

(18) Before attempting a repair, use an ohm-meter to verify that the fuse is open.If the fuse is good, then your problem is elsewhere, and this procedure won't help you.

(19) The repair procedure is to bridge the fuse "P" with a small strand of wire.It is barely visible in the photo.The "P" fuse is left in place, and the wire soldered across it to the left.This is a delicate operation and requires a fine tipped soldering iron, good eyesight and magnifying glass, and a steady hand.Use a teenager if necessary.

(20) Use the ohm-meter to verify continuity of the bridged fuse.Check for shorts or excess solder.

(21) Reassemble the unit.(No need to leave those dangerous voltages exposed for testing.)

(22) If all went well, the TV is now repaired.(My repaired TV has been operating for six months now.)

Sorry, FixYa is too screwed up and won't allow me to post the photo. FixYa really is a pain in the *** to contribute solutions to.Sorry, FixYa is too screwed up and won't allow me to post the photo. FixYa really is a pain in the *** to contribute solutions to.

Since you have sound on the stations this is a problem in the display. Take bright flashlight and hold it against the screen. Look for an image around the edge of the flashlight. If you see an image then its one of three problems;
1) The inverter board is bad.2) The CCFT (cold cathode fluoresent light) are bad.3) The power supply to the inverter board is bad.Someone knowledgeable in electronics can replace the bad part(s).

Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.

Most likely what happened is one of the capacitors went bad. When a capacitors goes bad it produces a popping sound. This could be an easy and cheap fix if you find the bad capacitor or capacitors. The bad capacitor will have a bulging top most likely on the power board but could be anywhere.

This sound like you are having problems with the power supply board. Since you are getting a momentary picture and sound the fuses are good but TVs today have "shorts" and "overvoltage" circuitry build in that will shut it down on errors. Someone knowledgeable in electronics will have to isolate the exact cause.

I had a problem with a Samsung 46 inch LCD and it had audio and dim light but no picture and found out that the logic board toward the top (inside tv) was bad and was no longer available and the only way to fix it was to get the entire display panel (the logic board came with it) It was not costwise to repair. Hope this helps.